<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=.333333">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<script src="./felxible.js"></script>

<style>
    body {
        margin:0
    }
    .dv {
        width:10rem;
        /* width:375px; */
        height:100px;
        background-color:deeppink;
    }
    @media (min-resolution:2dppx){
        body {
            background-color: orange;
        }
    }
    @media (min-resolution:3dppx){
        body {
            background:deepskyblue;
        }
    }
</style>

<body>
    <div class="dv"></div>
</body>
</html>